Based on my unpleasant experience with the WIA driver I want to contribute with this thread.

Windows WIA driver in combination with EPSON GT-S55 problems:

1. During scanning you get a dialog and you only see the progress bar.
2. Device Manager only returns the last page.
3. Scanner has capability to skip blank pages, but when you set the capability (4404) the device Manager will return an error when setting this capability.
4. Sometimes when you display the scan preview as base64 the page is not vertically aligned, sometimes it shows a little bit tilt to the left.